Methods and results of one year of balloon flights with biological specimens.

I N R E C E N T years Dr. Herman J. Schaefer 3 has shown that heavy primary cosmic ray particles can be expected to produce ionization tracks as long as several millimeters in living tissue. These tracks reach central ionization intensities of thousands of roentgens, and significant radial radiation to the order of cell diameters. Since no particle can be accelerated artificially to compare directly with the higher weight cosmic ray primaries, there has been considerable question concerning the exact biological effect of such particles. Recently Dr. Eugster of Switzerland has reported a track through human skin imbedded in nuclear emulsion, 2 and Dr. Yagoda has reported the passage of a heavy primary through vegetable fiber imbedded in emulsion. 4